<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>11.rem</title>
  <style>
    html {
      font-size: 100px;
    }

    div {
      font-size: .16rem;
      background-color: #ccc;
    }
  </style>
</head>
<body>
  <!-- rem是什么 -->
  rem是长度单位，他相对于根元素的font-size大小

  <div style="width: .6rem;">web</div>
  <div style="width: .2rem;">webweb</div>
  <div style="width: .3rem;">webwebweb</div>
  
</body>
</html>